Navigation has been, since ancient times, necessary for the development of economic and social activity. Navigation can also be essential in situations or environments in which safety of the navigator is not secured. The challenge in navigating accurately to a destination or direction is compounded with navigation instruments that have errors and/or in areas without connection to a satellite when attempting to use a global positioning system (GPS). For example, a soldier or sailor may depend on navigation systems and techniques to get to safety and may be unable to do so in GPS-denied areas.
All currently available image-based long-range land navigation techniques either conduct vision-based odometry or match images against landmarks stored in a database. Both of these techniques have disadvantages. Vision-based odometry only reduces the drift of an inertial navigation system (INS) solution, which is based on position and orientation, by automatically keeping track of arbitrary features in successive image frames as the platform moves. However, vision-based odometry itself has a position error growth rate as a function of distance traveled. In landmark matching, landmarks are sighted with an image sensor, e.g., camera or some other imaging sensor, including radar, after which the images are compared against existing imagery maps in an automated catalog system, providing a solution for the image sensor position and orientation. This solution can be precise, but suffers from several drawbacks. First, the landmarks need to be cataloged in a database and then must be visible to the image sensor. Second, the match-based positioning suffers from significant ranging and rotation errors due to the fact that slightly different perspectives of the landmarks, e.g., rotated to the left, right, front or back, appear the same to the image sensor, and thus result in an error in the image sensor position and orientation. Third, a comprehensive, stored, landmark database may be quite large, depending on the application, which requires large data storage memory.